Levels of carcinogenic chemical near Ohio derailment site far above safe limit

The EPA at the time proposed lowering the cleanup threshold to reflect the science around the highly toxic chemical, but the Obama administration killed the rules, and the higher federal action threshold remains in place.

The levels found in two soil samples are also up to 14 times higher than dioxin soil limits in some states, and the numbers point to wider contamination, said Linda Birnbaum, a former head of the US National Toxicology Program and EPA scientist.

The data probably confirms fears that the controlled burn of vinyl chloride in the days after the train wreck in the town created dioxin and dispersed it throughout the area, experts say, though they stressed the new data is of limited value because only two soil samples were checked.

Dioxins are a class of chemicals that are a byproduct produced when chlorine is burned, which is a common industrial process in making products like PVC.

The chemicals are highly persistent and can accumulate and stay for years in the environment or human bodies. Among other health issues, the compounds are linked to cancer, diabetes, heart disease, nervous system disorders and other serious health problems. Soil and food contamination are considered to be among the most common exposure routes.

Moreover, EPA scientists in 2010 put the cancer risk threshold for dioxins in residential soil at 3.7 ppt, and the agency recommended lowering the cleanup trigger to 72 ppt.

The EPA did not respond to specific questions from the Guardian, but in a statement the agency doubled down on its assessment.

It is also unclear where and at what depth the samples were collected, Prasse noted, all of which has implications for potential health risks in East Palestine. The chemicals would especially present a risk in dust and gardens, or for children playing outside, he added. Many homes are a matter of feet from the wreck site.

Moreover, if the soil that Indiana tested had been shipped to the state in a truck or train car, then it was mixed with other soil and probably diluted, which could make the soil appear safer than it is, and would conceal hotspots on the ground, Birnbaum said.

She noted the results revealed a wide range of dioxins, which suggests the chemicals were created in the vinyl chloride burn. Though dioxins are often present throughout the environment at low levels, especially in industrial areas like East Palestine, background profiles are usually limited to fewer types of dioxin, Birnbaum said.